Linn County and Cedar Rapids make progress on water quality projects

The county installed a new buffer, city installs bioreactor.

A water control tile line is installed Nov. 18 along a new saturated buffer off Highway 13 in Marion. In addition to imp
A water control tile line is installed Nov. 18 along a new saturated buffer off Highway 13 in Marion. In addition to implementing conservation strategies on its own land, Linn County has been working with farmers and landowners to come up with nutrient mitigation strategies in an effort to improve water quality in the Indian Creek and Upper Mississippi River watersheds. (Rebecca F. Miller/The Gazette)

MARION — Linn County and Cedar Rapids have made new strides this fall in their efforts to improve water quality and management in nearby watersheds.

The local governments have been working with other agencies and landowners to install projects meant to filter out more pollution and improve drainage — efforts that, when combined with similar work more broadly, help reduce the level of farm runoff getting into waterways.

On Nov. 18, Linn County partnered with multiple agencies to install a saturated buffer on farmland near the Solid Waste Agency.

The county collaborated with the federal and state agriculture departments, the Indian Creek Watershed Management Authority and the landowner to install the buffer, located on the corner of Highway 13 and Big Springs Road in Marion.

The Indian Creek Watershed Management Authority began in 2012 with Linn County and the cities of Cedar Rapids, Marion, Hiawatha and Robins partnering to reduce flood risk and improve water quality by developing a comprehensive plan for 93 square-mile area that drains into Dry Creek, Indian Creek, Squaw Creek and ultimately the Cedar River.

Linn County Soil Health Coordinator Emery Davis said a saturated buffer is an “edge of field” system that helps with drainage water.

The buffers reduce water pollution by intercepting drainage water from nearby farmland and absorbing nutrients like nitrates. Then they return the cleaner water to a drainage ditch, in this case contributing to Indian Creek, Davis said.


The county project is part of the Indian Creek Soil Health Partnership. Davis works with local farmers to help them improve soil health, which leads to cleaner water for residents of Linn County and beyond.

Indian Creek drains into the Cedar River, which flows into the Iowa River, which then drains into the Mississippi River.

In a 2018 investigation, The Gazette found that over a decade little progress had been made in 12 Midwestern states — including Iowa — in reducing nitrate and phosphorus going into rivers and streams that feed into the Mississippi River.

Pollutants from the states flow down to the Gulf of Mexico, where they contribute to an oxygen-deprived “dead zone” in which wildlife cannot survive.

Watershed management authorities are aiming to decrease the amount of nitrates and other pollutants caused by farm runoff through practices like promoting cover crops and installing saturated buffers and bioreactors.

Saturated buffers, like the one recently installed in Marion, have been found to reduce nitrate concentration by 42 percent on average for tile water flowing through them, according to data from the USDA Agricultural Research Service and Iowa State University.

Davis said the buffers cost between $2,000 and $3,000 and can last as long as water tiles, which can be over 50 years.

“These are fairly simple and inexpensive,” Davis said. “We get a good bang for the buck. We’re only in the first two years of this project and I think it’s been going very well.”

Cedar Rapids also is contributing to local water systems with its own watershed projects.


The city of Cedar Rapids installed its own bioreactor Nov. 5 on city-owned farmland adjacent to the Tuma Sports Complex, 3239 C Avenue Extension. The bioreactor is the city’s first.

Utilities Environmental Manager Mike Kuntz said a bioreactor is a trench filled with specialized wood chips that drainage water is routed through. Bioreactors also reduce water pollution by absorbing nutrients.

The new bioreactor will intercept drainage water and return cleaner water that contributes to Dry Creek.

“For us, it was a very affordable project,” Kuntz said. “For a private landowner, it could cost $15,000-20,000. For us, it was less than $10,000 since we used city labor and equipment.”

City Watershed Coordinator Mary Beth Stevenson said bioreactors are typically designed to handle 30 to 80 acres of farmland; the city’s land in this case is 123 acres.

“We hope to install some water monitoring into the bioreactor so we can analyze the results,” she said. “That’s going to be really important for us to know how effective it is.”

The project was a partnership between Cedar Rapids’ Parks and Recreation and Utilities Departments.

In 2015, the city took the lead role in the Middle Cedar Partnership Project with 16 partners including conservation groups, smaller watershed authorities, state agencies and farming associations to focus on managing water quantity and quality and soil health on 135,000 acres of the Middle Cedar River Watershed.


The watershed is 1.5 million acres. Various watersheds contribute to the 338-mile-long Cedar River, which begins in southern Minnesota and ends at the confluence with the Iowa River in Columbus Junction. The Iowa River flows into the Mississippi River.

Kuntz said a reason the city is engaged in watershed management is because Cedar Rapids is one of the leading cities in the nation that processes corn and soybeans as commodities.

Companies like PepsiCo, Cargill and General Mills use about 70 percent of the water from Cedar Rapids water treatment facilities. Cedar Rapids industries are also major supporters of the farm economy, using up to 1.5 million bushels of corn and 100,000 bushels of soybeans each day, Kuntz said.

“There’s a whole circle of impact that gauges on having success in the watershed,” he said.

With many projects and developments being heavily affected by the pandemic — as well as the August derecho in Iowa — watershed-related projects have still been progressing.

“This is actually a nice fall for these projects,” Stevenson said. “We actually did look at whether or not the wood chips for the bioreactor could be salvaged wood from the derecho, but unfortunately the wood chips needed have specifications with size and cleanliness.”

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